There is a VPS runing ubuntu 12.04.3 server on vmware esxi 5.
It has 2 valid static IPs and two network cards eth0 and eth1.
but only one of the assigned ips is pingable from outside. (both ips ang gateway is pigable from inside).it seems that I receive packets on dead IP, but don't reply them.
ifconfig will returns:

Without knowing what limitations you may be working with, why use two separate interfaces? From the looks of it, these two IPS are actually part of the same block. Why not just use an alias on eth0 for the second IP? If it's for bandwidth reasons you should consider setting up link aggregation(LACP, set up with the bonding kernel module) so both addresses can take advantage of the extra (virtual) nic. Assuming each virtual nic is connected to a separate real NIC (going to the same switch) you would also get redundancy for both IPs should one of the cables get pulled or a card goes bad on the VMware host.

you answer was illuminating; I guess I should go with IP aliasing and create eth0:0.
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r004Nov 29 '13 at 19:41

you answer was illuminating; i would go with IP aliasing and I do eth0:0. Now there is a couple of questions. first what should i do with the eth1; should I just leave it be. the second Q? is how should i write the directives for eth0:0. post-up /sbin/ifconfig eth0:0 91.121.247.148 netmask 255.255.255.255 broadcast 91.121.247.148 post-down /sbin/ifconfig eth0:0 down is it right?
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r004Nov 29 '13 at 19:53

You'll want to search elsewhere for that unfortunately. I spend my time in the RHEL/CentOS world. This howto looks like it would work. As for eth1, if it is connected to the same switch (I would imagine it is if it's vmware); I'd just shut it down for now. If you want to use bonding later you can but if these two virtual interfaces are connected to the same network under VMware, there's not much point in using it unless you need more throughput (and the VMware host actually has a faster uplink like 10Gbit).
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yoonixNov 30 '13 at 2:13

How to IP Alias in with this condition; I did the above and I got nothing. still 148 is not pingable from the outside.
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r004Nov 30 '13 at 6:18